The Gas Ventilation Calculator UK by Mr Combi Sales Ltd. is an essential tool for HVAC engineers. It is a full version application available for iPhone users. The app is a comprehensive guide to help find the required ventilation sizes for domestic flueless, open flue, and room-sealed appliances up to 70kW (net). It also includes an extractor fan calculator and a vent size calculator.

The app is designed to support multiple rooms, multiple appliances, and provides accurate ventilation sizes for all types of appliances. Its flueless calculator helps find the required vent size for flueless appliances such as cookers, grills, water heaters, and fires. The open flue calculator is used to find the required vent sizes for appliances with adventitious air or if the appliance is in a compartment. The app also provides a guide to remind you of the regulations for multiple appliances in one room.

The Gas Ventilation Calculator UK is easy to use and provides accurate results. It is an essential tool for HVAC engineers, and the app's vent size calculator helps find the total size of a vent with rectangular or circular holes. The app is available for iPhone users and can be downloaded from the App Store.